The XtAppGetSelectionTimeout
function returns the current selection timeout value, in milliseconds.
The selection timeout is the time within which the two communicating applications
must respond to one another. The initial timeout value is set by the selectionTimeout
application resource, or, if selectionTimeout is not specified, it
defaults to five seconds.

The XtAppSetSelectionTimeout function sets the
Intrinsics's selection timeout mechanism. Note that most applications should
not set the selection timeout.